1. Field of the Invention
The present invention relates generally to electrically stimulating medical devices having electrode contacts, and more particularly to manufacturing an electrode assembly having contoured electrode contact surfaces.
2. Related Art
A variety of implantable medical devices have been proposed to deliver controlled electrical stimulation to a region of a subject's body to achieve a therapeutic effect. Such devices, generally referred to herein as electrically-stimulating medical devices, include muscle or tissue stimulators, brain stimulators (deep brain stimulators, cortical stimulators, etc.), cardiac pacemakers/defibrillators, functional electrical stimulators (FES), spinal cord stimulators (SCS), pain stimulators, electrically-stimulating hearing prostheses, etc. Such electrically-stimulating medical devices include one or more electrode contacts which deliver electrical stimulation signals to the subject (commonly referred to as a patient, recipient, etc.; “recipient” herein). In addition, the electrically-stimulating medical devices may also include one or more electrode contacts to monitor and/or measure a particular biological activity, sometimes broadly referred to as sensors.
Electrically-stimulating hearing prostheses are typically used to treat sensorineural hearing loss. Sensorineural hearing loss occurs when there is damage to the inner ear, or to the nerve pathways from the inner ear to the brain. As such, those suffering from some forms of sensorineural hearing loss are thus unable to derive suitable benefit from hearing prostheses that generate mechanical motion of the cochlea fluid. Such individuals may benefit from electrically-stimulating hearing prostheses that deliver electrical stimulation to nerve cells of the auditory system. As used herein, a recipient's auditory system includes all sensory system components used to perceive a sound signal, such as hearing sensation receptors, neural pathways, including the auditory nerve and spiral ganglion, and the regions of the brain used to sense sounds. Electrically-stimulating hearing prostheses include, but are not limited to, auditory brain stimulators and cochlear implants.
Cochlear implants are often utilized when a recipient's sensorineural hearing loss is due to the absence or destruction of the cochlear hair cells which transduce acoustic signals into nerve impulses. Cochlear implants generally include an electrode assembly implanted in the cochlea. The electrode assembly includes a plurality of electrode contacts which deliver electrical stimulation signals to the auditory nerve cells, thereby bypassing absent or defective hair cells. The electrode contacts of the electrode assembly differentially activate auditory neurons that normally encode differential pitches of sound.
Auditory brain stimulators are often proposed to treat a smaller number of individuals with bilateral degeneration of the auditory nerve. For such recipients, an auditory brain stimulator comprises an electrode assembly implanted in the cochlear nucleus of the brainstem. The electrode contacts of the electrode assembly provide electrical stimulation signals directly to the cochlear nucleus.